Compilation of theoretical electron-impact excitation cross sections for Fe atomic ions

This compilation by the ORNL Controlled Fusion Atomic Data Center of excitation cross sections for Fe ions represents the first part of compilation of recommended collision cross sections for impurity ions of fusion interest. Extensions to other species and other processes is ongoing. Specifically compilation of excitation and electron capture data for C and O ions is currently in progress in collaboration with Japanese data centers. Data compilations for the processes of ionization and recombination are also needed. At present the Lotz formula is the best overall predictor for ionization cross sections with 0.85 of the Lotz formula found to be a slight improvement for ions +1 through +3. However, indirect processes such as excitation-autoionization can cause the Lotz formula to be an underestimate of ionization for specific ions, particularly heavy ions with three or more attached electrons. Recombination formulas are in use but are of highly uncertain reliability. Insufficient data and lack of any test of reliability for recombination preclude meaningful data compilation for this process at present